Property owners throughout rural Kansas are rushing to burn off unwanted vegetation before April 1, when most controlled fires are banned in 16 counties, including Sedgwick and Butler.

The rush could lead to smoke drifting into Wichita and other areas, despite permit rules aimed at reducing smoke in populated areas.

Friday, winds below 15 mph created good conditions for burning, and 12 controlled burns were under way Friday morning, including three that were more than 60 acres, said Ryan Mitchell, a shift supervisor for Butler County Communications.

Sedgwick County officials also expected to approve burning permits Friday, though the exact number wasn't available.

County officials have advised property owners to burn now to beat the April 1 ban, which was recently imposed to cut down on pollution during ozone season.

Wichita may face strict and costly regulations if it exceeds anticipated new ozone standards, and air quality data shows the city has been on the brink of exceeding that level for years.

Ranchers in the Flint Hills tend to burn off huge swaths of pasture in April. Environmental officials hope that the ban on open burning in counties surrounding the Flint Hills will mean the ranchland burning won't be compounded by local burning.

"It's not going to be a cure for it, but it shows the state of Kansas is complying with the safe air act," said Dan Wegner, a fire prevention captain with the Sedgwick County Fire Department.

Large burns in Butler and Sedgwick counties resulted in unusually heavy smoke passing through Wichita for about two hours Thursday afternoon. That spurred dozens of 911 calls about smoke, which irritated some peoples' eyes and lungs.

Wegner said firefighters respond to investigate all calls about smoke, tying up resources that may be needed for other emergencies.

"It overwhelms our system," he said.

He said people should check to see whether there is a fire nearby — not just drifting smoke — before calling 911.

In mid-March, the Kansas Department of Health and Environment warned that burning season had begun in the Flint Hills rangeland.

The burns improve forage for cattle, eliminate invasive species — such as eastern red cedar and sumac — and help minimize the danger of uncontrolled grass fires.

"If these burns take place when meteorological conditions do not disperse the smoke, air pollutants from the burns can affect persons in the Flint Hills and can be carried long distances to more populated areas," the state reported.

The state suggests people take precautions when smoke passes through, particularly if they have health issues.

Among the recommendations:

* Healthy people should curtail or avoid strenuous outdoor exercise.

* People with heart or breathing related illnesses should remain indoors.

* Help keep indoor air clean by closing doors and windows and running the air conditioner on "recirculate" setting.

* Keep airways moist by drinking lots of water.

* Contact your doctor if you have symptoms such as chest pain, chest tightness, shortness of breath or severe fatigue.